This invention relates to the buffing or finishing of objects of metal and other compositions and it has particular relationship to buffing materials and a method for making them flame-resistant.
A buffing wheel or buff typically includes a ring of metal from which extends an annulus of buffing material. Cotton fabric, polyester/cotton fabric, and sisal are commonly used as buffing material. The ring has teeth which engage the annulus of buffing material near its inner periphery and hold the buffing material in place.
In use, the buffing wheel is mounted on a drive shaft and is rotated. The rotating buffing wheel and the object to be buffed are in contact during the buffing process. Although buffing wheels are used singularly, common practice is to stack or gang a number of buffing wheels on a shaft for the purpose of buffing large objects like steel bumpers, aluminum extrusions and the like. Examples of buffing apparatus are disclosed in U.S. Pat. Nos. 2,805,530; 3,365,742; 3,706,167; 3,967,418; 4,799,338; 4,850,158; 4,882,880 and 5,560,744, the disclosures of which are incorporated by reference herein.
The buffing material (fabric and the like) from which layers in buffing wheels have been composed commonly include cotton and/or sisal. Sisal is a long coarse fiber that is twisted into strands and woven into a buffing material. Different buffing materials are used for different applications. In addition, the stiffness of the cotton buffing material may be regulated by the application of stiffening agents such as resins and ethylene vinyl acetates or polyethylene vinyl acetates either before or after the assembly of the buffing wheel.
In a typical buffing operation, a buffing compound such as an emulsion of hydrogenated fatty acids, water and abrasive grains is applied to the periphery of the buffing wheel. The buffing wheels are rotated at a high speed, typically 5000-9500 surface feet per minute. The object to be buffed makes contact with the buffing wheel during the process.
As the buffing wheels are used, the buffing material produces a dust and/or lint-like residue or swarf. Additionally, the buffing process generates metallic residue from the object being buffed. The residue from the buffing material and the metallic residue from the buffed object combine with residual buffing compound to form a highly-flammable buffing residue. Buffing residue as defined in this application includes the dust and/or lint-like buffing residue from the buffing material alone or with any combination of the metallic residue and/or the residual buffing compound.
Potential fires associated with this buffing residue are a serious concern. In order to avoid these fires, the buffing residue typically is removed by a conventional-type air exhaust system and is then collected in a collector, such as a bag house. The contents of the bag house must be removed often or the highly volatile contents may catch fire in the bag house through spontaneous combustion.
A second potential source of fire is from the buffing wheels themselves. Due to heat created by the various sources of friction (e.g., between the clinch ring and the drive shaft, the buffing material and the work piece, etc.) the buffing material is also at risk of catching fire during the buffing process.
The present invention provides a flame-resistant buffing wheel and a method of making same The buffing wheels of the present invention are comprised of a buffing material which has been treated with an flame-retardant solution. The buffing material may be treated either before or after the buffing wheels are assembled.
The flame-retardant solution includes a flame-retardant compound, and a penetrating agent which is applied to the buffing material. The treated buffing material is then allowed to dry. During tests of the treated buffing material over an open flame, no flame appears on the buffing material but the buffing material may smolder. The buffing residues resulting from the use of treated buffing wheels have also been found to be flame-resistant.
Advantages of this invention over prior systems are that in addition to rendering the buffing material flame-resistant, the buffing residues are also rendered flame-resistant.
The buffing wheels made in accordance with the present invention may be of any design presently known or contemplated in the future. Examples of known forms of buffing apparatus are illustrated in the drawings.